WEEK ONE - Introduction and erythrocytes Flashcards
OMSPT
State and describe 5 functions of the circulatory system
- carries o2 from lungs –> tissues and CO2 from tissues –> lungs
- transport metabolic waste to kidneys
- transportation of substrates from digestive tract –> liver
- via hepatic portal veins HPV
[blood contains nutrients + toxins from digested contents] - prevention of blood loss by platelets that initiate blood clotting
- regulates body temp by regulating blood flow
- blood –> skin = heat loss
- blood –> core = heat gain
Name and describe the components of the blood
adults have 4-6L of blood
blood = liquid CT w/ TWO main components
- plasma [90% water + 8% plasma proteins + 2% nutrients/hormones/gases/wastes]
- 55% of total blood volume
-buffy coat - <1% of platelets and WBC
- formed elements [RBC, WBC, platelets]
- 45% of total blood volume
Explain the importance of correct blood viscosity and osmolarity
Blood viscosity = resistance to flow
INCREASED RBC count = INCREASED blood pressure and volume –> more strain on the heart
Blood osmolarity = total molarity of dissolved particles [RBCs, Na+, protein]
- LOW osmolarity = fluid absorption into tissues → edema
- HIGH osmolarity = fluid absorption into blood → raises blood pressure
Describe the structure and function of erythrocytes and their relationship to hemoglobin
Disc shaped cell of 7.5 μm diameter and 2.0 μm thick at rim
Lacks organelles like mitochondria + anucleated
RBCs contain hemoglobin [red pigment molecule]
major function = gas transport of: - O2 → tissues
- CO2 → lungs
Majority of O2 [98.5%] in blood is transported within RBC attached to haemoglobin [Hb] molecules
- 280 million Hb molecules within a SINGLE RBC
State the normative values for hematocrit, hemoglobin concentration and red blood cell count and state reasons for differences between men and women
Hematocrit [% volume composed of RBCs]
m - 45 - 52%
f- 37 - 48%
Hemoglobin concentration
m - 13-18g/dL
f- 12-16g/dL
RBC Count
m - 4.6 - 6.2 million/ μL
f - 4.2 - 5.4 million/ μL
Values are LOWER in WOMEN
- Testosterone stimulates RBC production = less in women
- Women –> periodic menstrual losse
Describe the life cycle of RBCs including their production and disposal
lives for 120 days + produced in red bone marrow [erythropoesis]
erythropoesis takes 3-5 days - produces 2.5 millions RBC/ sec
= synthesis of hemoglobin, decrease in size + loss of ribsomes + nucleus = RBC cannot repair itself
haematopoetic stem cell –> colony forming unit erythrocyte –> erythroblast –> loses nucleus –> reticulocyte –> mature erythrocyte
disposal
- erythrocytes circulate for 120 days then break up in liver + spleen
- macrophages in spleen engulf+destroy –> Heme and globin portion is split
- iron core/heme group and salvaged and rest is disposed via faeces
- globin is hydrolyzed into AA
Describe how erythrocyte homeostasis is maintained
NEGATIVE feedback control
DROP in RBC count = hypoxemia [LOW blood oxygen]
Increased erythropoietin [EPO] output from kidneys = stimulates bone marrow to produce more RBC
erythropoiesis stimulation can also come from
- low O2 levels
- increase in exercise
- loss of
- emphysema [lung condition-shortness of breath]
Polycythemia and anemia; definitions, causes and effects
Polycythemia - HIGH RBC count / and or hematocrit
- effect
INCREASES in blood viscosity can → increase blood volume + pressure = strain on heart
causes
- dehydration
- bone marrow abnormalities
- blood doping and EPO use
- emphysema
Anemia = LOW RBC/hemoglobin count [hypoxia]
- effect
Tissues suffer from oxygen deprivation [tissue hypoxia] = shortness of breath/ lethargy
- body may compensate by increasing cardiac output –> can lead to cardiac failure
causes
- blood loss
- lack of b12 or folate absorption
- bone marrow abnormalities
- inadequate dietary intake of iron
Explain what determines a person’s ABO blood type
Determined by the presence of specific glycoproteins [antigens] on the membrane of a RBC
Type A person = A antigens + Anti-B antibodies
Type B person = B antigens + Anti-A antibodies
Type AB person - AB antigens + no antibodies
Type O = neither antigen [most common type] + Anti-A and Anti-B antibodies
Explain what determines a person’s Rh blood type
Rh+ = RBC has Rh protein
- people with Rh+ group have D antigens on RBC
Rh- = RBC LACKS Rh protein
Determine what blood types are compatible/incompatible with each other and understand the concepts of universal donor/recipient
Antigen-antibody reaction occurs when an antigen → mixed with its corresponding antibody
Type A person = A antigens + Anti-B antibodies
Type B person = B antigens + Anti-A antibodies
–> type B blood into a type a body would agglutinate [clump together]
agglutinated RBCs block blood vessels and hemolyse
- Free Hb blocks kidney tubules = causes death
Type AB → NO antibodies against antigens → therefore = universal recipients
Explain hemolytic disease of the newborn, why it occurs and how to prevent it?
Rh- mother and Rh+ child w/ incompatible blood types
- Mothers immune system recognises baby’s antigens [Rh+] as foreign –> produces antibodies that target cells carrying antigen for destruction
FIRST mismatch pregnancy is usually not at risk
Placenta separates mothers blood from fetal blood preventing exposure
During birth/abortion/miscarriage → placenta is TORN = places second pregnancy at risk
first pregnancy can be at risk if Rh- has been exposed to D antigen before eg
- blood transfusion/sharing needles
- trauma to placenta
Prevention
- Anti-D injection given to pregnant Rh- women
= binds and inactivates fetal agglutinogens in her blood before they stimulate immune response in mother during first pregnancy
State the relative abundance of each of the five leukocytes
WBCs grouped based on presence of cytoplasmic granules]
Granulocytes [presence of cytoplasmic granules]
- Neutrophils [60-70%]
- Eosinophils [2-4%]
- Basophils [<1%]
Agranulocytes [LACK granules]
- Lymphocytes [25-33%]
- Monocytes [3-8%]
Describe the structural characteristics and functions of each of the five leukocytes
Neutrophils
INCREASE in bacterial infections
3-5 lobed nucleus - mickey mouse shape
12 to 15 µm in size
Phagocytosis of bacteria [engulfment]
Release antimicrobial chemicals
Eosinophils
INCREASE in parasitic infections or allergies
10–20 μm in size
Phagocytosis of antigen-antibody complexes, allergens and inflammatory chemicals
Release antimicrobial chemical
+ enzymes to destroy parasites eg worms
Basophils
INCREASE in allergic inflammatory reactions
12 to15 µm in size
Secrete histamine [vasodilator] + heparin [anticoagulant]
Lymphocytes
round oval shape
INCREASE in diverse infections and immune responses
6-9µm in size
Destroy cell [cancer, foreign and virally infected cells]
Present antigens to activate other immune cells
Monocytes
jellybean shape
INCREASE in viral infections and inflammation
LARGEST WBC [16 and 22 µm in size]
Phagocytose pathogens and debris
Describe platelets and list 5 functions
Cell fragments [2-4 μm diameter] - formed from large red bone marrow [megakaryocyte]
- Platelets live for ten days
- Secretion of chemicals –> cause vasoconstriction of broken vessel walls + platelet aggregation
- Seal small break in injured blood vessels
- Secrete growth factors –> stimulate mitosis in fibroblasts + smooth muscle = aid is vessel wall repair + regeneration of tissues
- Initiate formation of clot dissolving enzyme
- Secretion of chemical –> attract neutrophils + monocytes to sites of inflammation
